While the invention can be applied and/or used in a variety of contexts, that is, for delivering fluid to a particular environment at preset, manually or automatically adjustable times in varying amounts, still the invention in the description set forth below will be directed to one of its principal uses, namely for supplying in a desired manner water to agricultural areas, irrigation systems, lawns, golf courses, and the like.
The system prevents a device which comprises an electronic system by which preset watering times can be automatically modified, if desired, to adjust for soil or plant needs. In a preferred embodiment of the invention, there is provided an electronic control box with one or more moisture sensors that will be placed in the ground. A programmable timer is used for each watering station. The timers employed can be separately set to the desired average watering time needed for the particular stations in question. An electronic clock is used, either internally or externally, to determine starting times for operation cycles.
The specific problem addressed, and one to which the prior art has not been particularly successful in addressing, is that of varying moisture-content cycle start conditions of areas to be treated such as, i.e., a golf course. Should the moisture content of such a course be relatively constant at start up times of the irrigation or sprinkler system, then there would be little problem in providing and timing a sprinkler system so that a given volume of water could be supplied over a given period and beginning at a specific time. The volume of water delivered, of course, will be determined by the length of time that a particular sprinkler branch is operating.
Problems arise, however, where initial start up moisture content conditions vary as, for example, at sprinkler times immediately after a rain storm, changes in moisture content owing to shady conditions and cloud patterns, rapid dry wind evaporation conditions, and so forth. What is desired, and what the present invention achieves, is an automatic system by which preset times for sprinkler operation can be automatically controlled or varied in accordance with ambient moisture conditions at the time of start up of each sprinkling cycle.
As to prior art the following U.S. patents have been noted:
U.S. Pat. No. 2,796,291, 3,024,372, 3,182,914, 3,238,392, 4,197,866, 4,216,789, 4,396,149, 4,684,920.
All of the above patents are relevant in connection with automatic or semi-automatic controls for sprinklers, including moisture-actuated controls.
The present invention differs from the above patents, both singly and taken in combination, in the following material respects: the present invention senses moisture content in the soil and uses this information to decrease or increase the preset water times according to the needs of the soil. Such decrease or increase in watering times will be in the form of a percentage added to or subtracted from each preset watering time. This approach makes it possible to use one ground moisture sensor to modify the watering times of many watering stations.
In the prior art as above recited, in contrast, there would be required a separate sensor for each watering station. Further, these would require water that is being applied to come in contact with the sensor to shut off the watering supply. The problems with such systems are as follows:
If the sensor is too close to the surface water being applied, then the same will shut off before enough water is delivered to reach lower root systems; if the sensor is deeper in the soil, then water being applied takes time to soak through the soil and reach the sensor. During this time an excess amount of water can accumulate on the surface, resulting in over-watering.
Also, prior art does not provide an automatic way in which additional moisture, i.e. moisture delivered longer than the preset time, can be added to the soil. This device also allows the user to set watering times for each station, and only modifies the time according to the needs of the soil in that particular area.